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Modern Weather Forecasts Are Stunningly Accurate (theatlantic.com)
An anonymous reader quotes a report from The Atlantic: Meteorologists have never gotten a shiny magazine cover or a brooding Aaron Sorkin film, and the weather-research hub of Norman, Oklahoma, is rarely mentioned in the same breath as Palo Alto. But over the past few decades, scientists have gotten significantly -- even staggeringly -- better at predicting the weather. How much better? "A modern five-day forecast is as accurate as a one-day forecast was in 1980," says a new paper, published last week in the journal Science. "Useful forecasts now reach nine to 10 days into the future." "Modern 72-hour predictions of hurricane tracks are more accurate than 24-hour forecasts were 40 years ago," the authors write. The federal government now predicts storm surge, stream level, and the likelihood of drought. It has also gotten better at talking about its forecasts: As I wrote in 2017, the National Weather Service has dropped professional jargon in favor of clear, direct, and everyday language. "Everybody's improving, and they're improving a lot," says Richard Alley, an author of the paper and a geoscientist at Penn State.
Understanding months-long events like El Niño, for instance, has allowed meteorologists to go beyond the seven-day forecast. Alley, the Penn State professor, says that he is awed by the new models. Well-studied features of Earth's climate -- like the temperate Gulf Stream in the Atlantic Ocean -- emerge in computer models, even though developers have written code that only mimics basic physics. We are now surrounded by the products of these miraculous models. In 2009, a back-of-the-envelope study estimated that U.S. adults check the weather forecast about 300 billion times per year. Perhaps in all that checking we have forgotten how strange the forecast is, how almost supernatural it is that people can describe the weather before it happens. More than 1,000 years ago, the Spanish archbishop Agobard of Lyon argued that no witch could control the weather because only God could understand it. "Man does not know the paths of the clouds, nor their perfect knowledges," he wrote. He cited the Book of Job for authority, which asks: "Dost thou know when God caused the light of his cloud to shine? Dost thou know the balancings of the clouds ?"
Understanding months-long events like El Niño, for instance, has allowed meteorologists to go beyond the seven-day forecast. Alley, the Penn State professor, says that he is awed by the new models. Well-studied features of Earth's climate -- like the temperate Gulf Stream in the Atlantic Ocean -- emerge in computer models, even though developers have written code that only mimics basic physics. We are now surrounded by the products of these miraculous models. In 2009, a back-of-the-envelope study estimated that U.S. adults check the weather forecast about 300 billion times per year. Perhaps in all that checking we have forgotten how strange the forecast is, how almost supernatural it is that people can describe the weather before it happens. More than 1,000 years ago, the Spanish archbishop Agobard of Lyon argued that no witch could control the weather because only God could understand it. "Man does not know the paths of the clouds, nor their perfect knowledges," he wrote. He cited the Book of Job for authority, which asks: "Dost thou know when God caused the light of his cloud to shine? Dost thou know the balancings of the clouds ?"
I do not doubt that significant progress has been made in modeling weather and predicting some aspects of future weather. But so far this only changed weather forecasts from being "mostly random, not better than just predicting that tomorrow's weather will be just the same as today's weather" into the current "we can state some trend that is reasonably likely to be correct for the next few days". I can still read weather forecasts from yesterday evening in the news that say "0% probability of precipitation today for the city I live in", while I see rain falling outside the window.
"Stunningly accurate" would be a whole different thing, like the forecast being able to tell me "rain will start to fall at my location from 10:34h to 11:27h tomorrow" - and that they very much still cannot.
Here in Norway we have learned to depend upon https://yr.no/ which provides both short-term (2+ days) and long-term forecasts:
When the short-term forecast states that it will be 0.5 to 0.8 mm rain (or snow equivalent) between 10:00 and 11:00 tomorrow, and that it will clear up starting at 13:00, this is very likely to be correct. If it isn't exactly right it is usually because the changes happen a little bit before or after the maximum likelihood prediction.
The presentation of the weather data is so good that many people in our neighboring countries have started to use YR instead of their local weather service.
Terje
"almost all programming can be viewed as an exercise in caching"
More than just lead time, increased processing power and bandwidth allows weather agencies to run the models more frequently. 10 years ago in Canada, the model only ran every 12 hours. Now they're routinely running it every 6. So short term model-based forecasts are using fresher observation data, which makes a huge difference in prediction quality since forecasts react quicker to unexpected changes. There's now less of that "they said we'd only get 2cm of snow when I went to bed, and I woke up to 10cm".
Another change that happened a while back (~25 years) is they stopped letting meteorologists mess with the longer range forecasts. They found that in terms of quality, the probability of a human improving on the model beyond 2-3 days was only 0.5 (i.e. half the time, they'd make the forecast better, and half the time worse), and the models have only gotten better since then. So they've focused human intervention on the short range high impact stuff (0-18 hours, mostly) and left the longer term predictions to the computers.
Log in or piss off.
"Cold front will arrive next Tuesday morning and lows will be in the teens and highs in the 30s by Thursday afternoon."
That's funny that you put it that way, because that's how they USED (~ 1980s) to predict the temperature: in the lower 70s, mid-20s, etc. Nowadays, all the TV stations here in Chicago give impossibly exact numbers: 32 for the high, 14 for the low, etc.
Weather forecasting hasn't got better, at all.
My Gran, rest her soul, was always far better at weather than any bloody meteorologist and that over her life of 95 years. Was she perfect? No, but a lot more use than any bloody meteorologist.
Add computers and satellites and they suddenly think they're all bloody geniuses.I'd actually say they're worse or the same. Probably get better results reading entrails.
I spoke to a guy at the UK met office about this in the 90s and he explained how they were basically compute limited. They run a number of sims with randomized perturbations at the start and see which outcomes are the most common across perturbations. They were using all their Crays full whack and that's what determined and limited the accuracy of the results. 30 years later, compute power is somewhat cheaper and my desktop is faster than one of those Crays.
I should use this sig to advertise my book ISBN-13 : 978-1501515132.